Drying and impregnating of cables



July 11, 1933. B 5 ELL 1,917,957

DRYING AND IMPREGNATING 0F CABLES Filed Jan. 6, 1931 lA/venffug V metically sealed erties, must then be sealed 0 economy is due to Patented July 11, 1933 enrreo S A-res PATENT ()FFICE BERNHARD SOPI-IUS FAITH ELL, Q2.

SEAT-ISA, SWEDEN, ASSEGNOR TO TELEFONAKTIE- BOLAGET L. M. ERIGSSON, OF STOCKHGLM, SWEDEN, A COMPANY OF SWEDEN,

DRYING AND nvnn-nenarrne on Cannes Application filed January G, 1931, Serial No. 507,037, and in Sweden February 7, 1930.

For drying and impregnating electrical.

cables, particularly high tension cables, herpots or heating vessels are commonly used in which the ables are placed and which may be evacuated or tilled with oil. In order to be more easy to handle, the cables are then generally put in crates or pertorated boxes which are inserted into the heating vessel. After the latter has bee closed it is evacuated to remove the humidity from the cable, heat being simultaneously supplied by external heating of said vessel by means of steam or electricity. Atterthe cable in this manner has been completely dried the heating vessel is filled with oil which is maintained at an excess of pressure of about four atmospheres. After com pleted impregnating the oil is tapped oil and the cable c atesremoved whereupon the vessel may be again used for drying and 1m pregnating a new set of cables. p

Apparatus of said kind are, however, comparatively expensive and are also uncco-.

nomical in operation. A cause of the bad the fact that the heat supcable during the evacuating takes place through radiation which results in aloss of heat and delays the heating of the cable. Another fact, which cooperates in increasing the costs, is that to the heating vessel aquantity of oil 18 supplied which is several times greater than the quantity required for impregnating the plied to the period only cables. The remaining oil, which during the impregnating period has been considerably deteriorated in regard to itselectrical propbe subjected to a special treatment before it may impregnating purposes.

The present invention has for its object to eliminate sai d inconveniences and consists substantially therein that the cable crates proper are formed as containers adapted to hermetically and to be evacuated and filled with oil. One or more cable containers designed in this manner may be inserted into a heating vessel in similar manner as the cable crate in the known arrangement in order to. heat the cable and the oil. By such adisposition the advantage is atagain be used for forded that the heatins vessel no lon er need to be designed to withstand ,the vacuum or excess pressure respectively required "for the drying and the impregnating procedures for which reason said vessel 'may be made cheaper. Further the heat supply to the cable maytake place more efficiently by that the cable containers ar e.dis )osed in a liquid bath whereby a greater heat economy and-a p shorter drying time fis obtained. Said ar rangement has further the advantage that the quantity of superfluous impregnating oil may be-considerably reduced as only the cable container need to be filled with oil. the cable container according to the inventioniis made annular the ditlerence between its volume and the volume of the cable may.

be reduced to. an insignificant value so that only a very small quantity of superfluous oil will remain after each impregnating pro-.

shownexainple the vessel is for the purpose 7 of heating provided with steam pipes 8 dis posed close to the bottom and the cylindrical side walls. The vessel as well as the lid is provided with a heat insulating covering 4 and 5 respectively. In the embodiment shown'on the drawing the vessel 1 is adapt ed to accommodate only one cable container 6. The latter consists of an annular plate vessel. which, upon being inserted in position in the heating vessel, rests upon a number of bars 7 disposed on the bottom of the vessel. The cable container 6 is provided with an annular lid 8 by means of which the container may be hermetically sealed. At

two. diametrically opposite points the lid is i A,

providedwith connecting plpes 9, 10 for connecting the container on the one side to an evacuating device 11 and, on the other side, to an oil container 12. The pipes 9, 10 extend through bushings 13, 14 in the lid 5 and are connected to the ievacuating. device 11 and to the oil container 12 respectively through pipe lines 19, 15 including shut off valves 16, 17.

After the cable 18 has been the cable container 6 so that it nearly fills the entire container, the latter is placed in position in the heating vessel 1 whereupon.

the lids 8 and Qare secured in position and the pipes 9, 10 connected to the pipes 19, 15. The vessel 1 contains preferably oil in such a quantity that the oil level reaches to the upper edge of the container 6. Thereupon the communication is opened with the evacuating device 11 so that the vacuum required for drying the cable is formed in the cable container During the evacuating period the cable is heated by steam circulating through the pipes 3 the heat transfer to the cable being mediated by the'oil in the yes sel 1 whereby the cable is rapidly heated. After completed drying the valve 17 is-initially opened so that the cable container .6, is gradually filled with oil whereupon the valve 16 is shut. During the subsequent impregnating periodthe oil in the cable container 6 is preferably held under an excess pressure of about fouratmospheres. At the same time the impregnating oil is held at a suitable temperature by supplying heat from the heating vessel. After completed impregnating the Valve 17 is shut wliere-- upon the cable container may be removed after, the'lids 2 and 8 have been detached and lifted.

and adapted to be separately closed up her-' 1. An apparatus for'drying and in'ipregnating cables, consisting of a heating vessel, a cable container placed inside said vessel metically. means in said heating vessel for heating the cable container. externally, an oil container, an evacuating apparatus, conduits connecting the cable container with said Oll container and evacuating apparatus, and means for shuttlng off the cable conrolled up in nating cables,

tainer alternately from'the oil container and the evacuating apparatus. 2. An apparatus for drying and impregconsisting of a heating vessel, a cable container placed inside said vessel and adapted to be separatelyclosed up hermetically, heating means for heating the cable container externally, a heat transferring fluid in the space between the walls of the heating vessel and the cable container, an" oil container, an evacuating apparatus, conduits connecting the cable container With the oil container and the evacuating apparatus, and means for shutting off the cable container alternately from the oil container and the evacuating apparatus.

'3. An apparatus fordrying and impregnating cables, consisting of an annular cable container, an annular cover for said con for said container covering the bottom and the inner and outer side walls of the con.- tainer, an oil container, an evacuating apparatus, conduits connecting the cable container With said oil container and evacuating apparatus, and means for shuttingoli' the cable containeralternately fr'om the oil container and the evacuating apparatus.

4. An apparatus for drying and impregnating cables, consisting of an annular heatingvessehan annular cable container placed inside said heating vessel and vadaptedto be closed up separately, heatingmeans in .the annular space between the walls ofthe heat ing vessel and the cable container, an oil container, an evacuating apparatus, con duits connecting the cable container with the, oil container and the evacuating apparatus, and means for shutting off the cable container alternately from the oil container and the evacuating vessel, I

In testimony whereof I aiiix my signature,

BERNHARD SOPHUS FAITH ELL, 

